researchers at vanderbilt university (nashville, tenn.) have created silver nanowires embedded with a polymer that dissolves in water that falls below 32 degrees celsius, which falls between body and room temperature, according to a report on the school’s website.

the circuit dissolves in cooling water. (vanderbilt university/youtube)

the nanowires were created using a store-bought cotton candy machine and a special polymer mix. the nanowires were similar in size, density, and complexity to capillaries in the human body and could be embedded in medical devices or implants or be used as capillaries in artificial organs.

“in this system, the silver nanowires are held together in the polymer so that they touch, and as long as the polymer doesn’t dissolve, the nanowires will form a path to conduct electricity similar to the traces on a circuit board,” the article explained. “trigger the polymer to dissolve by lowering the temperature, and the nanowire network disintegrates, destroying the conductive path.”

researchers used the nanowires to create a simple circuit board that currently can only turn on an led light. it works in water warmed by a hot plate, but when the heat source is removed and the water cools the circuit board dissolves.

dr. leon bellan, who led the research, said, “let’s say you use this technology to make an rfid wireless tag…you could implant important information in a person, and body temperature would keep it intact. if the tag were removed or the bearer died, it would dissolve. you could use it for implanted medical devices as well – to cause them to disintegrate, it would only require applying ice to the skin.”

the researchers will be working to integrate semiconductors to make transistors and to add wireless capability.

this research was recently published in applied materials and interfaces. the abstract read:

“the disintegration of transient electronic systems after a preprogrammed time or a particular stimulus (e.g., water, light, or temperature) is fundamentally linked to the properties and behavior of the materials used for their construction.

“herein, we demonstrate that polymers exhibiting lower critical solution temperature (lcst) behavior can work as thermoresponsive substrates for circuitry and that these materials can be coupled with conductive nanowires to form a transient electronics platform with unique, irreversible temperature-responsive behavior.

“the transient systems formed from composites of lcst polymers and conductive nanowires exhibit stable electrical performance in solution (t_solution > lcst) for over 24 h until a cooling stimulus triggers a rapid (within 5 min) and gigantic (3–4 orders of magnitude) transition in electrical conductance due to polymer dissolution.

“using a parylene mask, we are able to fabricate thermoresponsive electrical components, such as conductive traces and parallel-plate capacitors, demonstrating the versatility of this material and patterning technique.

“with this unique stimulus-responsive transient system and polymers with lcsts above room temperature (e.g., poly(n-isopropylacrylamide), methyl cellulose), we have developed a platform in which a circuit requires a source of heat to remain viable and is destroyed and vanishes once this heat source is lost.”

watch the circuit dissolve in the video below: